Charles duncan



C. DUNCAN.

ELECTRIC SWITCH CONSTRUCTtON.

umcmou rum act. 18. I919.

1,401,891, Patented Dec. 27, 1921.

m &

UNITED STATES CHARLES DUNOAN, 0! HOW, QUEBEC, CANADA.

ELECT-BIG SWITCH GONS'IBUOTION.

Specification 0! Letters Patent.

Patented Dec. 2'7, 1921.

.Applioation fled umber 18, me. sem No. 331,111.

To all whom it may concern:

Be it known that 1, CHARLES Duncan, :1 subject of the King of Great Britain, and resident of the city of Montreal, in the Province of Quebec and Dominion of Canada, have invented certain new and useful Improvements in Electric Switch Construction, of which the following is a full, clear, and exact description.

This invention relates to improvements in electric switches, and the rincipai object of the invention is to provi e a switch of the tumbler type which may be manufactured and sold at a low cost, and which will he durable and eflicient in operation.

A further object is to provide a switch so constructed that the working parts are ac cessible only from the back of the switch so as to be normally guarded against being tam cred with.

e main consideration in the construction of tumbler and other switches which are designed to be used by ersons unskilled in the handlin of electrical apparatus, is a quick make and break in order to reduce arcing to a minimum. For this reason springs are introduced into all switches otthis type and some times serve the further purpose of holding the switch in either open or closed position. It therefore developes that failure of the s ring will result in such slow operation o the switch that it soon becomes burned out or in the switch becoming inoperative by reason of its inability to remain either opener closed. In a at many tumbler switches the mechanism of the switch takes up so much room that the percelain base is necessarily weak in order to keep the switch within reasonable limits of size and the screw and conductor passages are formed through the base in what space is available without regard to their proper placin from a point of view of strength and nccessi ility.

According to the present invention the switch mechanism is of extremely simple and compact design enabling an extrernely strong porcelain base to be provided without increasing the size of theswitch beyond normal. The meehanismis so arran d that an ordinary helical spring in tension provides a resilient element. The screw and conductor passages are located clear of the mechanism and with proper regard for the strength of the base and the security of attschment.

In the drawings which illustrate the invention Fi re l'is a vertical sectional view of a tumbi r switch constructed according to this mgentign. fr

1g. is n a cute vertical sectio view at rlght engi es to l' i 1. m1

Fig. 3 1s a top plan view of the switch with the cap removed.

Fig. 4 1s a bottom plan of the switch with the back plates removed.

Ifig. 5 1s a fragmentary plan view of the casm as it appears when in position. Re err-mg more particularly to the drawmgs, 11 des gnates a porcelain base having a. centrally disposed, rectangular aperture 12 formed therethrough, above which is a brid e 18 s ertured at 14: for the passage of t c switc -throw lever. Screw passe 15 are provided in the plane 01': oscillation of the throw lever as near as possible to the peri ahery of the base, so that the base is secure in amunner best calculated to withstand the stresses imposed by the operation of the switch. Conductor passages 16 are formed one at each side of the central aperture 12 and entirely clear of all working parts of the sw tch. These passages are each approximntel y' equidistant between the passages 15. A pair of recesses 17 are formed in the base, one on each side of the central aperture 12 and adjacent conductor pass. for the reception of the terminals and binding posts. Recesses 18 are provided in thesides of the central aperture 12 to form journals for the circuit maker, and recesses 19 are formed in the sides of the slot 14 for the reception of the switch lever pivot. A recess 20 is formed around the central aperture 12 at the bottom of the base to receive the book cover.

The terminuls'21 and binding posts 22 are secured together and to the switch base by the usual screws 28 havin their heads located at the bottom of e base so as to be inaccessible when the switch is in use.

These screws are relieved of all bendin stresses by the embedding of the termin and binding pots in e porcelain base and, therefore, have no tendency to loosen. The terminals are located at one end of the central aperture 12 as clearly seen in Fig. 1. The circuit maker 24 is a substantially U- shaped member of a size to oscillate ireely in the recess 12 and to enter forclbl between the terminals. The extremities 5 of the arms of the circuit maker are outwardly tumed to project into the recesses 18 where the act as trunnions supporting the circuit m. er. The switch-throw lever 26 occupies the slot 14 and )rojccts at one end beyond the base, the end being threaded to receive :1 ball 27. The oppaosite end of the lever is bifurcated and one of the bifurcations 28 is connected through an insulator 29 conveniently by hooking or clenching the arms thron -h the insulator. The lever is supported by a pin 30 which passes through it and rests in the recesses 19 of the bridge. A helical spring 31 is connected at one end to the insulator between the bifurcations 28, and is connected at the opposite end to the central art of the circuit maker. It will be iiotecl ,in-Fig.. lthat the lever ivot 30 and circuit maker .trunnions 25 are oth locatcdin the central transverse plane of the switch and that the attachment of the spring is located in the central transverse plane of each of the lever and circuit makers.

-The bottonl'of the .aacrture 12 is closed by a cover plate 82, pro erably of insulating material, andtbe base and bridge are covered by a cover 33 having insulating lining 34.

While the cap may be attached inany suitable manner, such as by the usual screw thread connection with a. metallic member secured to, or forming, abridge and carry-in the throw-lever, it is preferred to adopt the construction illustrated as certain advantanes in the assembly of the mechanism are there obtained. The pin 30 is U-shapcd so that its extremities 35 project above the bridge. These extremities are outwardly turned so as to project beyond the pin receiving recesses 19 of the brid e. The cover 33 is provided with a centre aperture 36 at least large enough to permit the cover to be rotated about the U-shaped pin. Diametrically opposite notches 37 are formed in the periphery of the openin 36 to enable the cover to be passed over time out-turned ends 35 of the pm. Bosses or cams 38 are arranged in Jairs between the notches 37 and at diametrically opposite points at the edge of the aperture 36. The cams of each pair are spaced apart sufiicientl to hold the outturned pin ends 35 secure y between them.

In order to facilitate the rotation of the cover 33, necessary to attach and release some and also to conceal the porcelain bridge exposed throu h the cover openin 36. the top of the bri ge may be provided with a metal cap 39 having a centrally dis posed crown portion 40 which fits freely within the cover opening 36 and forms a central pivot about which the cover will turn easily. This cap is provided with a centrally disposed cruciform opening 41 for the passage of the lever and pin 30. The cap may be attached to the bridge in any suitable manner which will hold it against lateral or rotary motion as by the provision of down-turned lugs 42 enga ing recesses or flattened portions of the bri e.

The assembly of the switch is extremely simple. The circuit maker and switch-throw lever carrying the insulator are connected by the spring 31 and dropped into place from the back or bottom of the base. The ball 27 is then screwed onto the end of the lever to retain the parts and the lever drawn up until the pin 30 canbe inserted. The spring is now slightly in tension and holds the trunnions 25 of the circuit maker in their. recesses 18 and also holds the lever pin 30 in the recesses 19.. The cover 33 is then drop ed onto the base and rotated until the notches 37 pass the out-turnecl ends 35 of the pin 80. By the application of slight force .the cover may now be rotated and the ends of the pin will ride up out of the notches 37 onto the cover and will subsequently ride up over and drop between the cams 38 so that the cover will be releasably held against rotation.

The operation of the device is extremely sim lc. The tension of the spring applied to t e unsupported end of the circuit maker tends to throw the circuit maker against one end of the aperture 18 and at the same time inclines the lever until the lever and springs axes are in alinement, as clearly shown in Fig. l. The spring being in 51 qht tension ho ds the parts in this position. T0 operate the switch the lever is oscillu ted in the usual manner so that its lower end swings past the pivotal point of the circuit maker. In this action the spring is slightly tensioned until its point of attachment to the lever passes the pivotal point of the circuit maker, whereupon, it exerts a pull on the circuit maker to drawit to the opposite end of the aperture 12. This pull is due both to the movement of thelever and to the cont-ractive efiort of the tensioned spring. In actual practice the point of connection of the spring and lever gets some considerable distance beyond the ivotal point of the circuit maker before the iction between the circuit maker and the porcelain base is overcome, so that the action of the spring is very positive and the circuit maker is moved with extreme rapidity. Obviously the longer the movement of the circuit maker is delayed and the farther the point of spring connection with the lever passes the circuit maker pivotal point the greater will be the tension of the spring and the quicker the movement of the circuit maker. It will therefore be seen that a. certain amount of friction at the pivotal point of the circuit maker is desired. As the elongation of the spring is very little it is possible to use quite a strong spring. The use of a strong spring produces such movement of the circuit maker that it will force itself bet-ween quite heavy terminals,

.spring. After the cams are disen thus insur' a very d contact. The operation of e switc is exactl the same whether openin or closing but in the openiug movement t e friction between the circuit maker and the terminals is added to the friction of the circuit maker mounting, so that an increased tension is obtained in the sp with a consequent increase in the rapidity of action to a 'point where the arem period is so brief that the circuit maker MEI terminals are absolutely prevented from burning.

The spring, in addition to o crating the circuit maker, draws down on e lever and holds the extremities 85 of the pivot ti htly against the cover {38. It will be note that t ese in extremities 35 are out of parallel with t e central portion of the pin being turned toward the cover so that the load of the spring bears only upon the cover and the pm 15 sup orted clear of the cap 40 and the porcelain bridge. The result is, that at all times the cover is not be worked loose by v1 ration as frequently occurs with the ordinary screwed-on covers. If it is desired to remove the cover it is rotated to force the cams 38 under the pin extremities thereby elongatlng th;

e from the pin the cover is turned until he pin ends slip into the notches 37, whereupon, the cover may be lifted oii. The total rotation either applying or removing the cover is only one-quarter of a. revplutlon so that the cover may be very quickly and easily removed or applied.

ile the switch mechanism has been shown in connection with a particular base and cover constructionit will be readily understood that such a combination is not essential as the switch mechamsm may be ap plied to other bases and the cover may be secured in any suitable manner entirely independent of the lever pivot and spring.

The advent of the device are clearly defined and wi be readily apparent by'any one slrilled in the manufacture or installation of such apparatus but for convenience the same are briefly enumerated. The switch has a strong and energetic action which precludes buming of the circuit maker or terminals. The spring is of such tzpe and so arranged that maximum life t ereof is insured. The spring W111 positively hold the circuit maker in either open or closed switch position. The insulation between the handle and lcverllparts of the switch is ample. The cover w not become loose and fall off exposing the live parts of the switch, nor will the cover fastening become worn by use and inoperative. The cover may be ver, easily and quickly removed or applied as simplifying the work of installation. The screw and conductor passages are clear of the other parts of the tightl held and canth switch and the bindin Josts are readily accessible so that instal ation is further facilitated. The formation of the base and disposition of the fasteninis is such, that the maximum strength is o tained thereby increasing the life of the switch. The bridge conceals the working parts of the switch so that the same are protected against tampering or accidental damage when the cover is oif. The parts of the switch may be manufactured with extreme ease and rapidity and at a very low cost. Fewer assembling operations are required than in the manufacture of ordina switches and these operations are extreme y simple.

aving thus described my invention, what I claim is 1. In a switch, a base having a recess opening from its lower surface, terminals projcctin into said recess, a circuit maker oscillatab y mounted in the recess and circuit maker operating means projecting into e recess.

2. A device according to claim 1, in which the recess includes laterally directed, alined extensions thereof forming circuit bearings.

3. A device accordin to claim 1, in which the circuit maker is a shaped member having outwardly turned trunnions at the extremitics of its arms journaled in lateral extensions of the recess.

4. A device according to claim 1, in which the circuit maker comprises a U-shaped member pivotally mounted at the extremities of its arms, and in which the operating means is connected to the central part of the circuit maker and lies between the arms thereof.

5. A device according to claim 1, in which the circuit maker and operating means are removable from the recess toward the rear of the base and means engaging the circuit maker operating means and olding the operating means and circuit maker against removal.

6. A device according to claim 1, in which the recess extends in reduced size through the front surface of the base, the operating means only being movable through said recess in combination with a pivot pin passing throufgh the operating means on the front sur ace of the switch and holding the circuit maker and operating means against escape from the recess.

7. A device according to claim 6, in which is are provided at the front surface of the switch for the reception of said pin.

8. In a switch, a base havin a. centrally disposed a erture, a bridge on t e upper sur face of tie base spanning said aperture, terminals and a circuit maker located in said aperture and rendered inaccessible from the front of the base by reason of said bridge, and circuit maker operating means mounted on said bridge.

9. A device according to claim 8, in which the bridge is provided with a, slot extending from the upper surface thereof into communication with the base aperture, and in which the operating means includes :1 lever insertible at one end through the bridge slot and enlarged at its opposite end to prohibit passa 'c throughthe slot, and a pivot pin for said lever holding the same against escape from the bridge slot.

10. A device according to claim 8, in which the bridge is slotted from the outer surface to the base recess, and in which the circuit maker operating means includes a lever movable in said slot but impassable therethrough, an insulator carried by the lever and. a spring connected between the insulator and circuit maker holding the circuit maker to the lever, a pin passin through the lever above the bridge hoh ing the parts in operative position, and a head on the lever holding it against escape fromthe slot on removal of the pin, whereby the circuit maker is retained with the base.

11. A device according to claim 8, in which the base is provided with laterally directed recesses opening from the rear of the base and communicating with the central aperture, the bridge is slotted forming a. frontal outlet for the aierturc and in which the circuit maker in'c udcs trunnions movable into said recesses from the rear of the base, and the o berating means includes a lever oscillatable m the brid c slot, a pin gassing through said lever at the face of the ridge, and a spring in tension between the lever and circuit maker and holding the circuit maker trunnions in the recess and the pin a 'ainst the bridge.

12.111 a switch a base com osed of rough vitreous material, a pair 0% terminals, a metal circuit maker journaled in the material of the base, whereby the desired frictional resistance to movement of the circuit maker is obtained, and means for operating said circuit maker adapted to act thereon with gradually increasing force until the frictional resistance is overcome.

l3. In a svyitch, a pair of terminals, an oscillatable circuit maker, a circuit maker operatmgmember, an operating lever hai mg one end bifurcated, a non-conducting plate provided with end a. ertums receivmg the bifurcations of the lever therethrough and connected intermediate said bifurcations to one end ofsaid circuit maker operating member, the op Osite end of said member being connects to the circuit maker.

14. In a switch a base, a circuit making and breaking mechanism centrally disposed in said base and including an oscillatable lever, and attaching screw assages formed through said base in the p one of lever oscillation.

15. In a switch, a base having a recess, a pair of terminals carried by the base, a circuit maker oscillatable in the recess and journaled in opposite side walls thereof. said circuit maker being engageable with said terminals, and means for operating the circuit maker.

16. In a switch, a base havin a recess and an integral slotted bridge over anging said recess, a pair of terminals projecting into said recess, a circuit make-r engageable with said terminals and oscillatably mounted in the recess, and a pivotally mounted lever operatively connected to said circuit maker and operating in the slot in the bridge.

17 A switch comprising a pair of terminals, an oscillatable circuit maker engageable therewith, an oscillatable lever having a. bifurcated end, a non-conducting plate havi end apertures through which the bifurcations of the lever are extended and secured, and a tensioned spring havi one end secured to said plate between the ever bifurcations and the other end secured to the circuit maker, the points of attachment of the sprin being located in the central transverse p ane of each of the lever and circuit maker.

In witness whereof, I have hereunto set my hand.

CHARLES DUNCAN. 

